This invention relates in general to electrical connections and deals more particularly with a termination assembly formed by angularly related diverse electrical conductors which extend in transverse directions relative to each other in a region of connection therebetween.
Current automotive industry requirements mandate the transmission of electrical signals and power to electrical components carried by a steering wheel of a motor vehicle and connected by a resilient flexible wiring harness to other associated electrical components located at one or more fixed positions remote from the steering wheel. The number of circuit paths provided by such a wiring harness will vary depending upon the requirements of a particular vehicle. Power may, for example, be supplied by the wiring harness to an airbag deployment device associated with an airbag carried by the steering wheel upon occurrence of a predetermined condition such as a vehicular collision. The circuits may also provide electrical connection between components, such as switching devices, mounted on the steering wheel for operating a cruise control system and/or manually activating a signaling device or turn signal lamp mounted in fixed position on the vehicle at a location remote from the steering control apparatus. The wiring harness may also be employed to transmit signals to visual instrumentation mounted on the steering wheel in response to operation of remote sensors to indicate engine operation conditions or the like.
A wiring harness associated with the steering apparatus generally comprises a flat clock spring type wiring harness which facilitates relative rotational motion between the steering wheel and its supporting structure and includes a multi-conductor flexible flat cable (FFC) terminated at both of its ends by discreet electrically conductive members preferably disposed at right angles relative to the conductors which comprise the FFC. Examples of other automotive steering wheel wiring harnesses of the general type hereinbefore described and which require abrupt changes in direction at points of connection between diverse electrical conductors are found in U.S. Pat. No. 5,833,477 to Zahn for Device For Transmitting Electrical Signals Between Components Which Can Be Rotated Relative To Each Other, issued Nov. 10, 1998.
Heretofore two types of termination assemblies and methods have generally been employed to achieve electrical termination of a clock spring wiring harness within the circular motion environment hereinbefore discussed. Each termination assembly and method utilizes an intermediate element connected between an FFC and diverse conductors which terminate it to facilitate required abrupt directional change in the circuit paths provided by the harness. One such termination assembly and method utilizes a double sided printed circuit board (PCB) featuring plated through holes PTH to establish right angle terminations at opposite ends of a resilient FFC which comprises a flat clock spring wiring harness. The circuit paths on opposite sides of the circuit board are disposed at right angles relative to each other and connected by the PTH to provide right angle connection between the FCC and the diverse conductors which terminate it.
Another termination assembly and terminating method currently employed utilizes a stamped and formed lead frame molded into a plastic carrier to provide required right angle termination of an FFC which comprises the clock spring portion of a wiring harness. However, both of the aforedescribed assemblies and methods require two soldered or welded terminations to complete each 90xc2x0 input circuit to the FFC and two soldered or welded connections to complete each 90xc2x0 output circuit from the FFC, all of which adds substantially to the cost of producing a clock spring wiring harness. Further, the presence of numerous soldered or welded connections in the harness assembly introduces a serious risk of harness failure due to shock and/or vibration normally encountered in motor vehicle operation.
Accordingly, it is the general aim of the present invention to provide an improved clock spring wiring harness assembly which includes a resilient FFC terminated by diverse angularly disposed conductors wherein the diverse conductors are terminated directly to the FFC, thereby eliminating need for an intermediate terminating element such as a PCB or a lead frame, as hereinbefore discussed. It is a further aim of the present invention to provide an improved termination assembly and method for producing an array of 90xc2x0 terminations between diverse electrical conductors wherein each conductor is directly terminated to an associated conductor to provide a termination substantially immune to shock and vibration to increase mean time before failure (MTBF) and reduce production cost.
In accordance with the present invention an improved electrical termination is provided which comprises one axially elongated resilient electrical conductor having a termination portion, another axially elongated resilient electrical conductor having an electrical contacting portion, and a cradle assembly having a cradle and a cradle cap and made from ultrasonically weldable dielectric material. The cradle has an upwardly facing cradle surface and a cradle slot which extends through the cradle in a first direction of extent and opens through opposite sides of the cradle and through the cradle surface. The cradle slot receives and partially compliments the termination portion of the one electrical conductor and maintains an associated portion of the conductor in the first direction of extent in a region of termination defined by the slot. Aligning means is provided for positioning the contacting portion of the other electrical conductor in overlying electrical contacting engagement with the terminating portion of the one conductor and maintaining an associated portion of the other electrical conductor in a second direction of extent normal to the first direction of extent in the region of termination both during and after assembly of the cradle cap with the cradle. The termination further includes connecting means for securing the cradle cap in ultrasonically welded assembly with the cradle and continuously resiliently biasing said one and the other electrical conductors into electrical contacting engagement in the region of termination.